A system for treating liquids by forming bacteria flora using earthworm humus is disclosed. In some embodiments, the system includes a containment tank for receiving a contaminated liquid distributed through an opening into the tank, the containment tank further including a layer of earthworm humus through which the liquid is filtered, a medium layer for bacteria inoculation below the earthworm humus layer in the containment tank, and an inert layer below the medium layer proximate to the base of the containment tank.